Hi there,
Welcome to the Community. QuickBooks offers a variety of features that help you streamline your accounting. I'll be happy to share info and steer you in the right direction.
Based on what you've shared, I recommend making sure you're entering a tax rate when entering transactions. In case no tax codes are showing, I encourage you to check out this article here that shows you how to set up sales tax. Once you've set up the taxes, you can then use it to enter it on your line items.
You're welcome to ask other questions. I'm here to steer you in the right direction.